A BLAST of hot weather will drift south east through inland Australia this weekend, threatening many areas with extreme fire warnings.

In Southern states, a total fire ban is in place in Victoria and all but two districts of South Australia on Saturday.

Temperatures across much of Victoria and SA are set to exceed 40 degrees Celsius on Saturday. Hobart will peak at 33 on Saturday.

Gusty northerly winds will move through ahead of a trough on Saturday.

Weatherzone meteorologist Tom Hough said fire danger ratings are likely to reach Extreme, or potentially Catastrophic, in some areas.

Temperatures will drop into the mid-to-low 30s in Victoria and SA on Sunday in southern parts of the states, as a cool change moves through.

Total fire bans have been issued across Victoria and all but 2 districts of SA on Saturday. Fire danger ratings will reach Extreme in parts of both states and may reach Catastrophic (Code Red in Victoria) in some areas: https://t.co/ia3rEWVTXppic.twitter.com/YFxs0WxxqC